Optimal Object Placement Device and Method

1. An optimal object placement device which optimizes, in an information processing system having a storage area in each of a plurality of sites and in which a user can access objects stored in the storage area of all of the sites from each of the sites, placement of each of the objects, comprising: an access tendency detection unit which detects an access tendency as a tendency of continuity of the user's access to the objects, which include a first object and a second object, and determines whether access by the user of the first object and the second object occurs consecutively a number of times equal to or greater than a prescribed threshold; and an object transfer control unit which executes, upon determining the access by the user of the first object and the second object occurs consecutively a number of times equal to or greater than the prescribed threshold, when the user accesses a first object from a second site which is different from a first site having the storage area storing the first object, control for transferring in advance, to the storage area of the second site from which the first object was accessed, the second object, wherein the object transfer control unit: executes control for copying in advance the second object to the storage area of the second site when the second site is a relatively rare site as the site used by the user for accessing the first object; and executes control for migrating in advance the second object to the storage area of the second site when the second site is not a relatively rare site as the site used by the user for accessing the first object.

2. The optimal object placement device according to claim 1 , further comprising: a difference synchronization control unit which executes, when the second object copied to the second site is updated, control for reflecting the update in the second object of a copy source stored in the storage area of the first site.

3. The optimal object placement device according to claim 2 , further comprising: a copy object deletion control unit which executes, when the second object copied to the storage area of the second site is not accessed for a given period of time, control for deleting the copied second object from the storage area of the second site.

4. The optimal object placement device according to claim 1 , wherein a part or all of the sites include the storage area of a plurality of storage tiers each having a difference access speed to the respectively stored objects, and wherein the optimal object placement device further comprises: a transfer tier control unit which determines, based on an evaluation of the user regarding an access speed to the second object after transferring the second object to the storage area of the second site, the storage tier of a transfer destination upon subsequently transferring the second object.

5. An optimal object placement method to be executed by an optimal object placement device which optimizes, in an information processing system having a storage area in each of a plurality of sites and in which a user can access objects stored in the storage area of all of the sites from each of the sites, placement of each of the objects, comprising: a first step of detecting an access tendency as a tendency of continuity of the user's access to the objects, which include a first object and a second object, and determining whether access by the user of the first object and the second object occurs consecutively a number of times equal to or greater than a prescribed threshold; and a second step of executing, upon determining the access by the user of the first object and the second object occurs consecutively a number of times equal to or greater than the prescribed threshold, when the user accesses a first object from a second site which is different from a first site having the storage area storing the first object, control for transferring in advance, to the storage area of the second site from which the first object was accessed, the second object, wherein, in the second step: control is executed for copying in advance the second object to the storage area of the second site when the second site is a relatively rare site as the site used by the user for accessing the first object; and control is executed for migrating in advance the second object to the storage area of the second site when the second site is not a relatively rare site as the site used by the user for accessing the first object.

6. The optimal object placement method according to claim 5 , further comprising: a third step of executing, when the second object copied to the second site is updated, control for reflecting the update in the second object of a copy source stored in the storage area of the first site.

7. The optimal object placement method according to claim 6 , further comprising: a fourth step of executing, when the second object copied to the storage area of the second site is not accessed for a given period of time, control for deleting the copied second object from the storage area of the second site.

8. The optimal object placement method according to claim 5 , wherein a part or all of the sites include the storage area of a plurality of storage tiers each having a difference access speed to the respectively stored objects, and wherein the optimal object placement method further comprises: a transfer tier control step of determining, based on an evaluation of the user regarding an access speed to the second object after transferring the second object to the storage area of the second site, the storage tier of a transfer destination upon subsequently transferring the second object.